1. Field of the Invention
The present invention relates to a packaging for integrated circuits, and more particularly, to a socket for testing a ball grid array (hereinafter referred to as BGA) package and-a test method using the socket.
2. Description of the Related Art
After fabrication of semiconductor devices, an electrical die sorting (EDS) test determines which of the devices are good. The good devices are packaged and electrically tested further. In the testing, the packaged devices are placed in sockets corresponding to their package forms. Plastic packages having outer leads have been widely used in the industry. However, many packages such as ball grid array packages, fine-pitch ball grid array packages, and chip scale packages have solder balls or solder bumps as external terminals.
Sockets for the testing have various methods of construction and shapes according to the outer forms of packages. That is, in the case where the packages have a dual in-line package (DIP) form, a small out-line package (SOP) form, a quad flat package (QFP) form, or a BGA package form, the shape and construction of the sockets are each different.
As the size of electrical devices have become small these days, the packages using solder balls or solder bumps have replaced packages using leads.
Typical sockets for testing the BGA package having solder balls or solder bumps include POGO pins that contact the solder balls or the solder bumps. Such sockets are disclosed in U.S. Pat. No. 5,545,050, which is herein incorporated as reference in its entirety.
The POGO pins can cause several problems in testing the BGA package.
First, when the tips of the POGO pins being used for a channel connection means are connected to the solder balls or the solder bumps, the POGO pins may scratch and damage the solder balls or the solder bumps, producing visual defects such as burrs.
Second, since the POGO pins are constructed to have a pin type in number xe2x80x9c1xe2x80x9d shape, the POGO pins connect solder ball/bump pads to a socket board, even if the solder balls or the solder bumps are not attached to a package body of semiconductor devices due to mistakes in assembling. Accordingly, a defective BGA package in which the solder balls or the solder bumps are not attached cannot be detected.
To solve the above problems, it is a first object of the present invention to provide an apparatus for testing a BGA package capable of connecting solder balls as the external terminals of the BGA package to a tester by using a pressure conductive rubber (hereinafter referred to as a PCR) and a mesh and thereby preventing damage to the solder balls and accurately detecting a defective BGA package in which the solder balls are not attached.
It is a second object of the present invention to provide a method for electrically testing the BGA package.
To achieve the first object of the present invention, there is provided an apparatus for testing a BGA package. The apparatus includes: a socket board having a channel connection means; a middle connection unit composed of a PCR attached to the socket board; a mesh having holes in which solder balls are inserted and being attached to the middle connection unit; and a frame unit attached to the edges of the middle connection unit and the mesh, for fixing and aligning the middle connection unit and the mesh, including an alignment means.
According to an embodiment of the present invention, the socket board is a plane having a plurality of POGO pins as the channel connection means.
According to another embodiment of the present invention, the socket board is a plane having a printed circuit pattern as the channel connection means.
According to still another embodiment of the present invention, the BGA package is a strip-type package including a unit package or several packages attached to one strip.
It is preferable to further include a contactor, which applies pressure to the BGA package so that the external terminals of the BGA package contact the middle connection unit via the mesh.
Preferably, the PCR of the middle connection unit contains conductive particles including nickel (Ni) and gold (Au), and the conductive particles are vertically arranged in a silicon rubber, and the frame unit includes a supporting board of the middle connection unit, a height-adjusting means, and an alignment means for aligning the middle connection unit and the height-adjusting means.
To achieve the second object of the present invention, there is provided a method for electrically testing a BGA package, comprising the steps of: loading the BGA package on a pressure conductive rubber; aligning the solder balls of the BGA package in holes of the mesh of the socket; connecting the solder balls to conductive particles of a PCR via the mesh by applying pressure to the upper part of the BGA package; connecting the conductive particles of the PCR to a channel connection means of a socket board; and connecting the channel connection means to channels of a tester.
According to preferred embodiments of the present invention, a plane having the POGO pins or a plane having the printed circuit pattern can be used for the channel connection means. The BGA package may be constructed of a unit package or several packages. Preferably, the mesh forms several holes in which the solder balls of the BGA package are inserted.
According to the present invention, damage or variation occurring in the external terminals can be prevented by using the middle connection unit and the mesh as a means for connecting the socket board to the solder balls as the external terminals of the BGA package. Also, errors in an open/short test can be reduced by smoothly connecting the external terminals and the socket board to each other. Thus, a defective BGA package in which the solder balls are not attached can be accurately detected in a final electrical test.